Which One of These Is Not a Good Guideline to Follow

Multiple Choice

Which one of these is not a good guideline to follow when creating tables in a relational database?

A) Design first, create tables later
B) Name tables systematically, using conventional "tbl" prefixes
C) Use mnemonic names for data fields
D) Assign at least 50 characters to each text field
E) Use consistent data types for primary and foreign key fields in database tables